I just use Eclipse(free programming IDE) and NetBeans(another free programming IDE, but specifically for Java) to make some for my own personal use(reason being because they're not really "market worthy" as far as their capabilities. Just checking up on system information, etc. But I strongly recommend you make a few apps, and put them on the market as free. That way, you can start to get your name out, so that people know you develop good things. Then if you have a good idea, start charging for it. A little goes a long way though: If you charge $0.99 for it, and 5 people download it per day, you make $150 per month, just on that one app.